源码为:
#include <iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ifaddrs.h>
using namespace std;
int main(void) {
struct ifaddrs* myaddrs;
struct sockaddr_in *ss, *kk;
if (getifaddrs(&myaddrs) == 0) {
for (struct ifaddrs* ifa = myaddrs; ifa != NULL; ifa = ifa->ifa_next) {
ss = (struct sockaddr_in*) ifa->ifa_addr;
kk = (struct sockaddr_in*) ifa->ifa_netmask;
if (ss->sin_family == AF_INET)
cout << "sa_family:" << ss->sin_family << " " << ifa->ifa_name << ":" << inet_ntoa(ss->sin_addr) << " netmask:" << inet_ntoa(kk->sin_addr) << endl;
}
}
return 0;
}
为什么得到的ip地址和子网掩码一样?
我感觉linux下的inet_ntoa打印子网掩码有问题,这段程序在Mac系统上可以正确输出。
我自己写了个函数,可以输出正确结果。
#include <iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ifaddrs.h>
#include <sstream>
using namespace std;
string getip(const sockaddr_in* addr)
{
ostringstream s;
int a = ntohl(addr->sin_addr.s_addr);
s << ((a >> 24) & 0xFF) << '.' << ((a >> 16) & 0xFF) << '.'
<< ((a >> 8) & 0xFF) << '.' << (a & 0xFF);
return s.str();
}
int main(void)
{
struct ifaddrs* myaddrs;
struct sockaddr_in *ss, *kk;
char buf[100];
if (getifaddrs(&myaddrs) == 0) {
for (struct ifaddrs* ifa = myaddrs; ifa != NULL; ifa = ifa->ifa_next) {
ss = (struct sockaddr_in*) ifa->ifa_addr;
kk = (struct sockaddr_in*) ifa->ifa_netmask;
if (ss->sin_family == AF_INET)
cout << ifa->ifa_name << ":" << getip(ss) << " netmask:" << getip(kk) << endl;
}
}
return 0;
}
利用inet_ntop
函数可以得到正确的结果